A conventional ray-tracing method has been optimized to predict the wave propagation characteristic in a frequency band of the mobile communication of 10 GHz or less. Mobile communication systems to be introduced in the future use remarkably shorter wavelength of mm wave or sub-mm wave band more than 6 GHz and thus has a limit of employing the radio wave tracking method. Accordingly, it is necessary to more accurately approximate the progress of the radio wave and the magnitude of the received signal to a receiver.
FIG. 1 is a conceptual diagram illustrating the determination of a reception radius in a ray launching method of a related art.
Referring to FIG. 1, a three-dimensional ray-tracing method starts a ray-tracing by applying the ray launching method. In the ray launching method, the maximum number of rays emitted from a virtual spherical body is set to be N, the rays (where n={1, 2, 3, . . . , N}) is individually emitted in a space in order.
The rays ‘n’ emitted from a transmission point 100 are individual incident on a surrounding material and terrain and then are changed in their directions through diffraction and reflection. Finally, the rays pass through the reception radius 104 defined about the reception point 102 to determine the presence or absence of reception of the rays. Such series of procedures refers to as a ray-tracing. The rays that enter the reception radius are treated that the track thereof has been completed, and a following track is progressed on a subsequent ray to be emitted. In this case, the track completion may be determined by whether the rays have passed through the reception radius.
FIG. 2 illustrates the problems occurred due to a method of determining a reception radius in accordance with a related art. When using the method of determining the reception radius, the difference in a distance between the transmission point 100 and the receiving point 102 causes problems that a double counting and a dead zone occur. These problems originate from the reason that the magnitude of all rays entering the reception radius is treated to be ‘1’. Owing to that, reducing the magnitude of the reception radius entails the increase of a shadow area and increasing the magnitude of the reception radius entails the increase of an overlap calculation more and more, which acts as a factor that increases the error in the wave propagation characteristic.